COA substrate and display panel

ABSTRACT

A color-filter on array substrate, having a first base substrate, includes a plurality of thin-film transistors (TFTs) disposed in an array on the first base substrate; color resists correspondingly disposed on one of the TFTs; a planarization layer disposed on the color resists and covering all of the color resists; and an electrically conductive layer disposed on the planarization layer. An orthogonal projection of the electrically conductive layer on the planarization layer covers the planarization layer. The electrically conductive layer comprises a plurality of first regions and second regions being separated. Each of the first regions is electrically connected to one of the TFTs. One of a plurality of protrusions is provided by the planarization layer or at least one of two adjacent color resists and corresponds to one of the second regions.

CROSS REFERENCE TO RELATED APPLICATIONS

The present disclosure claims priority of China Patent application filedwith the National Intellectual Property Administration on Dec. 10, 2019,application number is 201911253718.0 and the title is “COA Substrate andDisplay Panel”. The content of the application is cited and incorporatedin the present disclosure in its entirety.

FIELD OF INVENTION

The present disclosure relates to the field of display technologies, andmore particularly, to a color-filter on array substrate and a displaypanel.

BACKGROUND OF INVENTION

According to liquid crystal optics theory, in the operation of verticalalignment liquid crystal (VA LCD), a transmittance is defined asT=0.5*sin 2(2φ)sin 2(pi*Δnd/λ). The azimuth φ of liquid crystals isrequired to be deflected to 45 degrees so that the polarizationdirection of the incident light is deflected by 90 degrees after passingthrough the liquid crystal layer to make the transmittance extremelyhigh. Therefore, in the existing VA LCD design, the pixel electrodes arearranged at 45 degrees in the horizontal/vertical direction so that theliquid crystal molecules can be arranged in the direction of φ=45degrees when the voltage is applied to drive the liquid crystalmolecules.

In a color-filter on array (COA) liquid crystal display, a conventionalpixel electrode is formed on a second passivation layer (PV2), then thepixel electrode is patterned and formed, and polyimide (PI) coating andalignment processes are performed. The second passivation layer isgenerally made of silicon nitride (SiN). Because silicon nitride needsto be manufactured by a chemical vapor deposition (CVD) process, only acoating process is required by the planarization layer (polymer film onarray, PFA). Therefore, in the prior art, a planarization layer is oftenused to replace the structure of the second passivation layer on oneside of the COA substrate. Now, the passivation layer of many productsis changed from a silicon nitride material to a planarization layer toimprove the limited capacity problem of the CVD process.

However, because the planarization layer is affected by chemicalprocesses during synthesis, impurities and ions are easily be to left.Especially after LCD devices are manufactured, it is easy for ionprecipitation to occur in the planarization layer, which causes ions toenter the liquid crystal layer and affect its resistivity and results inimage sticking.

One of the reasons that the ions in the planarization layer easily enterthe liquid crystal layer is that the patterned pixel electrodes on thearray side generate a periodic slit angle and line/space periodicstructures. The PI alignment film disposed between parts of theplanarization layer and the liquid crystal layer has a weak capacity ofblocking ions. On the other hand, after the PI alignment film is invadedby ions, resistivity and capacitance change so that image stickingresult is affected.

A double-layer pixel electrode on a planarization layer at the arrayside of a COA substrate is also provided in the prior art to block ionpenetration of the planarization layer. However, this technologyrequires regulation of the electrical properties and it adverselyaffects 45-degree electric field for patterning pixel electrode. Thus,the process is more complicated.

Technical Problems

The present disclosure provides a COA substrate and a display panel. Anelectrically conductive layer covering the planarization layer isprovided on a planarization layer. The electrically conductive layerincludes a plurality of first regions and second regions disposedbetween two adjacent first regions. Each of the first regions of theelectrically conductive layer is electrically connected to a thin-filmtransistor. The adjacent first regions are disconnected and the secondregions are separated. Segmentation separation occurs at the boundarybetween the electrically conductive layer and the color resists, whichcan make the electrically conductive layer work independently in asingle pixel unit without short circuiting and can effectively preventthe planarization layer from generating ion penetration into the liquidcrystal layer. Thus, the problem of image sticking is improved.

SUMMARY OF INVENTION

The present disclosure provides a color-filter on array (COA) substrateand a display panel. The electrically conductive layer covering theplanarization layer is provided on the planarization layer. Theelectrically conductive layer includes the plurality of first regionsand second regions disposed between two adjacent first regions. Each ofthe first regions of the electrically conductive layer is electricallyconnected to a thin-film transistor. The adjacent first regions aredisconnected and the second region are separated. Segmentationseparation occurs is at the boundary between the electrically conductivelayer the color resist, which can make the electrically conductive layerwork independently in a single pixel unit without short circuit and caneffectively prevent the planarization layer from generating ionpenetration into the liquid crystal layer. Thus, the problems of imagesticking are improved.

First, the embodiment of the present disclosure provides a COAsubstrate, having a first base substrate, comprising: a plurality ofthin-film transistors (TFTs) disposed on the first base substrate; colorresists, wherein each of the color resists is correspondingly disposedon one of the TFTs; a planarization layer disposed on the color resistsand covering all of the color resists; and an electrically conductivelayer disposed on the planarization layer; wherein an orthogonalprojection of the electrically conductive layer projecting on theplanarization layer covers the planarization layer, the electricallyconductive layer comprises a plurality of first regions and secondregions disposed between two adjacent one of the first regions, each ofthe first regions is electrically connected to one of the TFTs, and thefirst regions and the adjacent second regions are separated; and whereinthe planarization layer is provided with a plurality of firstprotrusions, each first protrusion is corresponding to an area of one ofthe second regions, or the color resists are provided with a pluralityof second protrusions, at least one of two adjacent one of the colorresists is provided with one of the plurality of second protrusions, andthe plurality of second protrusions correspond to the plurality of firstprotrusions.

In the COA substrate, a surface of the first protrusion contacted withthe electrically conductive layer and a surface of the first protrusioncontacted with the planarization layer are formed at least one undercutstructure.

In the COA substrate, a surface of the second protrusion contacted withthe electrically conductive layer and a surface of the second protrusioncontacted with the color resists are formed at least one undercutstructure.

In the COA substrate, an area of a side of the first protrusion facingthe electrically conductive layer is greater than an area of anotherside of the first protrusion opposite to the side facing theelectrically conductive layer.

In the COA substrate, the COA substrate further comprises a plurality ofpixel units, wherein each of the pixel units is provided with one of thecolor resists.

In the COA substrate, the COA substrate further comprises the via holesare disposed in the color resists in each of the pixel units anddisposed in the planarization layer covering the color resists, and eachof the first regions of the electrically conductive layer is connectedto one of the TFTs through one of the via holes.

Second, the present disclosure provides a COA substrate having a firstbase substrate, comprising: a plurality of thin-film transistors (TFTs)disposed in an array on the first base substrate; color resists, whereineach of the color resists is correspondingly disposed on one of theTFTs; a planarization layer disposed on the color resists and coveringall of the color resists; and an electrically conductive layer disposedon the planarization layer; wherein an orthogonal projection of theelectrically conductive layer projecting on the planarization layercovers the planarization layer, the electrically conductive layercomprises a plurality of first regions and second regions disposedbetween two adjacent one of the first regions, each of the first regionsis electrically connected to one of the TFTs, and the first regions andthe adjacent second regions are separated.

In the COA substrate, the planarization layer is provided with aplurality of first protrusions, each first protrusion is correspondingto an area of one of the second regions.

In the COA substrate, a surface of the first protrusion contacted withthe electrically conductive layer and a surface of the first protrusioncontacted with the planarization layer are formed at least one undercutstructure.

In the COA substrate, at least one of two adjacent one of the colorresists is provided with one of a plurality of second protrusions, andthe plurality of second protrusions correspond to the plurality of firstprotrusions.

In the COA substrate, a surface of the second protrusion contacted withthe electrically conductive layer and a surface of the second protrusioncontacted with the color resists are formed at least one undercutstructure.

In the COA substrate, an area of a side of the first protrusion facingthe electrically conductive layer is greater than an area of anotherside of the first protrusion opposite to the side facing theelectrically conductive layer.

In the COA substrate, the COA substrate further comprises a plurality ofpixel units, wherein each of the pixel units is provided with one of thecolor resists.

In the COA substrate, the COA substrate further comprises the via holesare disposed in the color resists in each of the pixel units anddisposed in the planarization layer covering the color resists, and eachof the first regions of the electrically conductive layer is connectedto one of the TFTs through one of the via holes.

Third, the present disclosure provides a display panel comprising theabove-mentioned COA substrate, wherein the display panel furthercomprises an opposite substrate and a liquid crystal layer disposedbetween the COA substrate and the opposite substrate, wherein theopposite substrate comprises a second base substrate and an electrodelayer disposed on the second base substrate, and each of the colorresists is corresponding to one of openings provided in the electrodelayer.

In the display panel, the opposite substrate further comprises aplurality of black matrixes corresponding to boundaries of adjacent oneof the color resists.

Beneficial Effects

In comparison with present technologies, in the COA substrate and thedisplay panel provided by the present disclosure, the electricallyconductive layer covering the planarization layer is provided on theplanarization layer. The electrically conductive layer includes theplurality of first regions and second regions disposed between twoadjacent first regions. Each of the first regions of the electricallyconductive layer is electrically connected to a thin-film transistor.The adjacent first regions are disconnected and the second region areseparated. Segmentation separation occurs at the boundary between theelectrically conductive layer and the color resist, which can make theelectrically conductive layer work independently in a single pixel unitwithout short circuiting and can effectively prevent the planarizationlayer from generating ion penetration into the liquid crystal layer.Thus, the problem of image sticking is improved.

DESCRIPTION OF DRAWINGS

FIG. 1A illustrates a structural diagram of a normal array substrate ofexisting technologies.

FIG. 1B illustrates a structural diagram of a color-filter on arraysubstrate of existing technologies.

FIG. 2 illustrates a color-filter on array substrate and a display panelof a first embodiment of the present disclosure.

FIG. 3 illustrates a simple structural diagram of a color resist, aplanarization layer, and an electrically conductive layer of thecolor-filter on array substrate shown in FIG. 2.

FIG. 4 illustrates a color-filter on array substrate and a display panelof a second embodiment of the present disclosure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present disclosure provides a color-filter on array (COA) substrateand a display device. In order to clarify the technical solutions ofembodiments of the present disclosure, the present disclosure isdescribed by the embodiments in detail accompany with drawings.Obviously, the mentioned embodiments are utilized to clarify the presentdiscloser rather than limit the present disclosure.

Please refer to FIG. 1 which illustrates a structural diagram of anormal array substrate of existing technologies. As shown in FIG. 1A,the array substrate includes a first base substrate 11, a plurality ofTFTs 12, a passivation layer 13, and a pixel electrode 16 which aresubsequently stacked. The TFT 12 includes a gate 121 disposed on thefirst base substrate 11. A gate insulating layer 122 is disposed on thegate 121 and covers the gate 121 and the first base substrate 11. Anactive layer 123 is disposed on the gate insulating layer 122. Aninsulating layer 125 is disposed on the active layer 123 and covers theactive layer 123 and the gate insulating layer 122. A source and drain124 are disposed on the insulating layer 125. The passivation layer 13is disposed on the plurality of TFTs 12 and covers the source and drain124 and the insulating layer 125. The array substrate further includesscan lines disposed on the same layer as the gate electrode 121 andsignal lines disposed on the same layer as the source drain 124. FIG. 1Aalso illustrates a color filter substrate disposed opposite to the arraysubstrate. The color filter substrate includes a second base substrate21, a plurality of black matrixes 22, a second electrically conductivelayer 23, and a plurality of color resists 14 disposed between thesecond base substrate 21 and the second electrically conductive layer23. The color resists 14 are red color resist, green color resist, andblue color resist (not shown in drawings). Each of the color resists 14is located between two adjacent black matrixes 22. The secondelectrically conductive layer 23 is a common electrode. The blackmatrixes 22 are disposed corresponding to positions of the scan lines orthe signal lines.

Please refer to FIG. 1B which illustrates a structural diagram of acolor-filter on array (COA) substrate of existing technologies. The COAsubstrate 01 includes a first substrate base 11, a plurality of scanlines formed on the first base substrate 11, a plurality of data linesdisposed perpendicular to the scan lines, and a plurality of pixel unitsdefined by the scan lines and the data. Each of the pixel unitsincludes: a TFT 12, a passivation layer 13 covering the TFT 12, andcolor resists 14 disposed on the passivation layer 13. The COA substrate01 also includes a planarization layer 15 covering all of the colorresists 14. The COA substrate 01 further includes a pixel electrode 16disposed on the planarization layer 15 and located within the pixelunits. Each of the color resists 14 of the pixel unit may be a red colorresist, a green color resist, and a blue color resist (not numbered).The red color resist corresponds to red pixel units, the green colorresist corresponds to green pixel units, and the blue color resistcorresponds to blue pixel. The TFT 12 includes a gate 121 disposed onthe same layer as the scan line, a gate insulating layer 122 disposed onthe gate 121 and covering the gate 121, a semiconductor layer 123disposed on the gate insulating layer 122, an insulating layer 125disposed on the semiconductor layer 123 and covering the semiconductorlayer 123, and a source and drain 124 disposed on the insulating layer125 and disposed on the same layer as the signal line. FIG. 1B alsoshows a pair of opposite substrates 02 disposed opposite to the COAsubstrate 01. The opposite substrates 02 include a second base substrate21, a plurality of black matrixes 22, and a common electrode layer 23which are sequentially stacked. The black matrixes 22 are disposed atpositions corresponding to the scan lines or the signal lines.

The difference between the COA substrate 01 shown in FIG. 1B and theconventional array substrate shown in FIG. 1A is that a plurality of thecolor resists 14 shown in FIG. 1B are provided on one side of the COAsubstrate 01, a planarization layer 15 is provided on the plurality ofcolor resists 14, and the planarization layer 15 covers all of the colorresists 14. In the COA substrate 01 shown in FIG. 1B, the pixelelectrode 16 is patterned in the opening area. Different patterned pixelelectrodes can be designed by using 2/4/8 domains, etc., but althoughthe penetration improves transmittance and viewing angles of the liquidcrystal, the patterned pixel electrode 16 easily lets ions penetrate theplanarization layer 15 so that the resistivity of the liquid crystallayer is affected and image sticking occurs.

Please refer to FIG. 2 which illustrates a color-filter on arraysubstrate and a display panel of a first embodiment of the presentdisclosure. The present disclosure discloses a COA substrate 1 having afirst base substrate 11. The COA substrate 1 includes a plurality ofTFTs 12 arranged in an array on the first base substrate 11. Each of theTFT 12 corresponds to a color resist 14. A planarization layer 15 isdisposed on the color resist 14 and covers all of the color resists 14.An electrically conductive layer 16 is disposed on the planarizationlayer 15. An orthographic projection of the electrically conductivelayer 16 on the planarization layer 15 covers the planarization layer15. The electrically conductive layer 16 includes a plurality of firstregions 161 and second regions 162 disposed between two adjacent firstregions 161. Each of the first regions 161 is electrically connected toone of the TFTs 12. The adjacent first regions 161 and the secondregions 162 are separated.

Please refer to FIG. 3 accompanying with FIG. 2. FIG. 3 illustrates asimple structural diagram of a color resist, a planarization layer, andan electrically conductive layer of the color-filter on array substrateshown in FIG. 2.

In this embodiment, the planarization layer 15 is provided with aplurality of first protrusions 151 in locations corresponding to each ofthe second regions 162. Each of the first protrusions 151 of theplanarization layer 15 corresponds to a boundary between two adjacentcolor resists 14. Each of the color resists 14 may be a red colorresist, a green color resist, or a blue color resist. Each of the firstprotrusions 151 is integrated to a structure of the planarization layer15.

An area of a side of the first protrusion 151 facing the electricallyconductive layer 16 is greater than an area of another side of the firstprotrusion 151 opposite to the side facing the electrically conductivelayer 16. More particularly, a surface of each of the first protrusions151 contacting the electrically conductive layer 16 and a surface of theplanarization layer 15 forms at least one undercut structure 17 (taperangle). Each of the first protrusions 151 further includes at least oneinclined sidewall 152. An inclined angle formed between the inclinedsidewall 152 and the surface of the planarization layer 15 in the areaof the undercut structure 17 is less than 90°.

Preferably, the first protrusion 151 is an inverted tapered protrusionor inverted trapezoidal protrusion. The inverted tapered protrusion orinverted trapezoidal protrusion forms a structure with a high taperangle during the manufacturing process. The planarization layer 15, theinverted tapered protrusion, or the inverted trapezoidal protrusion ismade of transparent organic photoresists.

In this embodiment, in the present disclosure, a half tone mask (HTM) isused to manufacture the planarization layer 15 and the first protrusion151 so that the first protrusion 151 has significant step differences atthe boundary of any adjacent pixel units.

In this embodiment, because the first protrusion 151, the undercutstructure 17, and the electrically conductive layer 16 are deposited onthe planarization layer 15 and the first protrusion 151 over the entiresurface. The electrically conductive layer 16 is deposited on the entireside of the planarization layer 15 and the first protrusion 151 facingaway from the first base substrate 11 in the manufacturing process. As aresult, the first regions 161 and the second regions 162, which areseparated, are formed due to a high step difference of the electricallyconductive layer 16 at each of the first protrusions 151.

In the present disclosure, as a preferred embodiment, the TFT 12includes a gate electrode 121 disposed on the same layer as the scanlines. A gate insulation layer 122 is disposed on the gate electrode 121and covers the gate electrode 121. A semiconductor layer 123 is disposedon the gate insulating layer 122. A passivation layer 125 is disposed onthe semiconductor layer 123 and covers the semiconductor layer 123 andthe gate insulating layer 122. A source and drain 124 are disposed onthe passivation layer 125 and on the same layer as the signal lines. Inother embodiments, the TFT 12 may also be a top gate structure, which isnot specifically limited herein.

In the present disclosure embodiment, the COA substrate 1 includes aplurality of pixel units, and the orthographic projection of thescanning line and the signal lines on the first base substrate 11defines a plurality of the pixel units. Each of the pixel units isprovided with one of the color resists 14. The pixel units correspond tored pixel units, green pixel units, and blue pixel units respectively.The planarization layer 15 covers all pixel units and the color resists14. It should be noted that via holes (not shown) are provided on thecolor resists 14 in each of the pixel units and the planarization layer15 covering the color resist 14, so that the first regions 161 of theelectrically conductive layer 16 are electrically connected to thesource and drain 124 of the TFT 12 through the via holes.

Please refer to FIG. 2 and FIG. 3.

The difference between the COA substrate 1 in the present disclosure andthe COA substrate 01 in the prior art shown in FIG. 1B is that in theCOA substrate 1 described in the present disclosure embodiment, theplanarization layer 15 is provided with one of the first protrusions 151which is disposed corresponding to each one of the second regions 162.Each of the first protrusions 151 contacts a surface of the electricallyconductive layer 16 and a surface of the planarization layer 15 to formthe undercut structure 17 (taper angle). And the electrically conductivelayer 16 is deposited on the entire surface of the planarization layer15 and the first protrusion 151. The electrically conductive layer 16 isseparated due to high steps at each of the first protrusions 151, andthereby the first regions 161 and the second regions 162 are formed. Theelectrically conductive layer 16 completely covers the planarizationlayer 15. Each of the first regions 161 of the electrically conductivelayer 16 corresponds to one of the pixel units. Each of second regions162 covers the first protrusion 151. An orthogonal projection of theelectrically conductive layer 16 on the planarization layer 15completely covers the planarization layer 15 so that the liquid crystallayer can be effectively prevented from ions permeability by theplanarization layer 15. Thus, image sticking is improved. Moreover,because the first regions 161 and the second regions 162 of theelectrically conductive layer 16 are disconnected one by one at thefirst protrusion 151, the first regions 161 can make any adjacent pixelunits independently work without short circuiting.

Please refer to FIG. 2. The present disclosure also discloses a displaypanel including the COA substrate 1. The display panel further includesa pair of opposite substrates 2 opposite to the COA substrate 1. The COAsubstrate 1 is provided in the display panel. A liquid crystal layer(not shown) and an alignment film (not shown) are between the COAsubstrate 1 and the opposite substrate 02. The COA substrate 1 and theopposite substrate 2 form a liquid crystal box. The opposite substrates2 include a second base substrate 21, a plurality of black matrixes 22disposed on the second base substrate 21, and an electrode layer 23disposed on and covering the black matrixes 22 and the second basesubstrate 21. The black matrixes 22 correspond to a boundary of adjacentcolor resists 14. The black matrixes 22 correspond to the scan lines ordata lines of the TFTs 12. In order to achieve multi-domain display ofthe display panel, the electrode layer 23 is provided with at least onepatterned opening (not shown) corresponding to each of the color resists14.

Please refer to FIG. 4 which illustrates a second embodiment of a COAsubstrate and a display panel of the present disclosure. As shown inFIG. 4, the difference between the second embodiment and the firstembodiment is that the color resist 14 includes a red color resist 141,a green color resist 142, and a blue color resist 143 in the secondembodiment. At least one color resist 14 of two adjacent color resists14 is provided with a second protrusion 144 corresponding to the secondregions 162. Each of the second protrusions 144 and at least one of thecolor resists 14 are an integrated structure. The surface of the secondprotrusion 144 contacting the planarization layer 15 and the surface ofthe color resist 14 form at least one undercut structure 17 (taperangle). Each of the second protrusions 144 further includes at least oneinclined sidewall 145. The inclined angle formed between the inclinedsidewall 145 and the surface of the color resist 14 in the area of theundercut structure 17 is less than 90°. And in this embodiment, theheight of the planarization layer 15 is same. The planarization layer 15covers the color resist 14 and the second protrusion 144. Theelectrically conductive layer 16 is deposited on the entire surface ofthe planarization layer 15. The electrically conductive layer 16 isseparated and disconnected at the second protrusion 144 due to high stepdifferences.

In the second embodiment of the present disclosure, the electricallyconductive layer 16 and the planarization layer 15 are separated anddisconnected due to high step differences at each of the secondprotrusion 144 because the second protrusion 144, the undercut structure17, and the electrically conductive layer 16 are entirely deposited onthe surface of the planarization layer 15, and the planarization layer15 covers all the color resists 14 and the second protrusion 144, whichleads to a naturally consequent formation of first regions 161 and thesecond regions 162. The orthographic projection of the electricallyconductive layer 16 on the planarization layer 15 completely covers theplanarization layer 15. The electrically conductive layer 16 can alsoprevent the of the planarization layer 15 from ion educt. The purpose ofreducing the image sticking is achieved by the disconnection of theelectrically conductive layer 16 at the second protrusion 144 which canalso prevent short circuiting between adjacent pixel units.

In the above embodiments of the present disclosure, the electricallyconductive layer 16 and the electrode layer 23 are both indium tin oxide(transparent ITO), which is not limited in other embodiments.

In the above embodiments of the present disclosure, a plurality of theTFTs 12 are disposed on the first base substrate 11, but in otherembodiments, a plurality of the TFTs 12 can also be disposed on otherlayers. For example, a plurality of the TFTs 12 are disposed between theplanarization layer 15 and the color resist 14 and they are not limitedthereto.

Specific implementations of embodiments can refer to the above-mentionedembodiments, and details are not described herein again.

To conclude, the present disclosure disposes the electrically conductivelayer 16 covering the planarization layer 15, disposes the plurality offirst regions 161 and second regions 162 between two adjacent firstregions 161 in the electrically conductive layer 16, and electricallyconnects each first region 161 of the electrically conductive layer 16to one of TFTs 12. The adjacent first regions 161 and the second regions162 are separated. The electrically conductive layer 16 has segmentationseparation corresponding to the boundary between the color resists 14,which can make a single pixel unit work independently without shortcircuiting and can effectively prevent the planarization layer 16 fromion penetrating into the liquid crystal layer 15 because theorthographic projection of the electrically conductive layer 16 on theplanarization layer 15 entirely covers the planarization layer 15.Therefore, the problem of image sticking is improved.

It should be noted that for a skilled person in the art, equivalentreplacements or modifications can be obtained according to the technicalsolution and the aspects of the present disclosure fall into theprotection of the attached claims of the present disclosure.

What is claimed is:
 1. A color-filter on array (COA) substrate having afirst base substrate, comprising: a plurality of thin-film transistors(TFTs) disposed in an array on the first base substrate; color resists,wherein each of the color resists is correspondingly disposed on one ofthe TFTs; a planarization layer disposed on the color resists andcovering all of the color resists; and an electrically conductive layerdisposed on the planarization layer; wherein an orthogonal projection ofthe electrically conductive layer projecting on the planarization layercovers the planarization layer; the electrically conductive layercomprises a plurality of first regions and second regions disposedbetween two adjacent first regions, each of the first regions iselectrically connected to one of the TFTs, and the first regions and theadjacent second regions are separated; and the planarization layer isprovided with a plurality of first protrusions, each first protrusioncorresponds to an area of one of the second regions, the firstprotrusion extends away from the first base substrate and comprises atop end away from the first base substrate and a bottom end adjacent tothe first base substrate, the first protrusion further comprises anundercut structure defined on two sides of the bottom end of the firstprotrusion, and an area of the top end of the first protrusion isgreater than an area of the bottom end of the first protrusion.
 2. TheCOA substrate according to claim 1, wherein at least one of two adjacentcolor resists is provided with one of a plurality of second protrusionsextending away from the first base substrate, each second protrusioncorresponds to each first protrusion and comprises a top end away fromthe first base substrate and a bottom end adjacent to the first basesubstrate, the second protrusion further comprises an undercut structuredefined on two sides of the bottom end of the second protrusion, and anarea of the top end of the second protrusion is greater than an area ofthe bottom end of the second protrusion.
 3. The COA substrate accordingto claim 1 further comprises a plurality of pixel units, wherein each ofthe pixel units is provided with one of the color resists.
 4. A displaypanel comprising the COA substrate according to claim 1, wherein thedisplay panel further comprises an opposite substrate and a liquidcrystal layer disposed between the COA substrate and the oppositesubstrate, wherein the opposite substrate comprises a second basesubstrate and an electrode layer disposed on the second base substrate,and each of the color resists is corresponding to one of openingsprovided in the electrode layer.
 5. The display panel according to claim4, wherein the opposite substrate further comprises a plurality of blackmatrixes corresponding to boundaries of adjacent color resists.